1. Field of the Invention
The present invention relates to a charged-particle beam exposure apparatus which draws a pattern on a substrate by a charged-particle beam, and a method of manufacturing an article using the same.
2. Description of the Related Art
An electron beam exposure apparatus draws a pattern on a substrate, mounted on a stage, by blanking an electron beam, emitted by an electron gun, in accordance with drawing data while scanning the stage in the sub-scanning direction and scanning the electron beam in the main-scanning direction. The blanking is an operation of switching irradiation and unirradiation of the substrate with the electron beam. Controlling the timing of this switching also makes it possible to control the time in which a unit region is irradiated with the electron beam. The drawing data is generated from circuit design CAD data and is bitmap data of a circuit pattern. The drawing data has pixels corresponding to the resolution of a circuit. The drawing data can have a size of about 10 Tbytes per chip at a line width of, for example, 22 or 16 nm.
When the data size is large, an error may occur in the drawing data for various reasons. Examples of conceivable error factors include electrical noise and jitter during data transmission, and an error generated by a memory which stores the data. When an error occurs during transmission, correct data must be retransmitted. In case of the error generated by the memory, drawing data must be read out again or generated again. Due to these error factors, it may become impossible to prepare correct drawing data until a predetermined blanking timing. Also, due to a fluctuation in processing load upon generating drawing data, it may become impossible to prepare data at a predetermined blanking timing.
To prevent the stop of drawing due to delay of drawing data, a method of transmitting and accumulating it in advance in a buffer memory provided near a blanker is available. With this method, even if the drawing data is delayed, drawing can be continued using the data accumulated in the buffer memory, thus preventing degradation in throughput.
Japanese Patent Laid-Open Nos. 2001-196297 and 7-111945 describe electron beam exposure apparatuses which return the position of a stage to that before interruption of drawing, when it restarts drawing.
Unfortunately, the method of providing a buffer memory increases the cost and mounting scale in proportion to the size of the buffer memory. This problem is serious especially in the recent electron beam exposure apparatus because it draws a pattern simultaneously using a large number of electron beams to improve the throughput. Therefore, a buffer memory must be prepared for each electron beam. This means that a considerable number of buffer memories must be prepared for a total number of electron beams although each individual electron beam requires only a small buffer capacity. Since a buffer memory must be provided near the blanker, it is impossible to ensure a given mounting space and, in turn, to mount a buffer memory having the required capacity.
The electron beam exposure apparatuses described in Japanese Patent Laid-Open Nos. 2001-196297 and 7-111945 return the position of the stage to that before interruption of drawing, when it restarts drawing. Therefore, the stage moves to the position before interruption of drawing, and it takes a considerable time for the stage to reach a predetermined scanning speed by reacceleration, thus degrading the throughput.